Produce chambers have been known for subjecting produce in produce crates to controlled atmosphere. Typically, the produce is held in produce crates and controlled atmosphere is introduced into the chamber and allowed to expose the produce in the produce crates to the controlled atmosphere. The produce crates typically have openings in the side walls to allow the controlled atmosphere to reach all of the produce within the crates. Efficient flow of controlled atmosphere through the crates is not always guaranteed. In some cases, produce may escape exposure to the controlled atmosphere because of the way in which the controlled atmosphere is passed to the crates. Further, it is known that crates can be stacked in multiple height tiers within chambers and that a blind or tarp like curtain is placed over each layer to control the way in which the controlled atmosphere passes through the crates in each layer. A typical example of a produce chamber of the latter type is disclosed in our U.S. Pat. No. 5,041,298.